Sys.WebForms.BeginRequestEventArgs.updatePanelsToUpdate Property
Gets a list of UniqueID values for UpdatePanel controls that should re-render their content, as requested by the client.
Note
To get or set property values for client API properties, you must call property accessor methods that are named with the get_ and set_ prefixes. For example, to get or set a value for a property such as cancel, you call the get_cancel or set_cancel methods.
var updatePanelsToUpdate = arg.get_updatePanelsToUpdate();
Return Value
An array of UniqueID values for UpdatePanel controls.
Remarks
Server-side processing might update additional UpdatePanel controls.